The National Marker Company sign displays the legend ?CAUTION - WHEELS MUST BE CHOCKED BEFORE LOADING AND UNLOADING? in yellow text on a black base with black text on a yellow base. This caution sign is often used in the loading-unloading area of industrial facilities, warehouses, and construction sites. It informs drivers or workers that a vehicle?s wheel must be chocked before loading or unloading the cargo. The sign is compliant with OSHA 29 CFR-1910.145 standard and has an NMC Sign Muscle coating that protects the text against fading, scratches, scuffing, mold, and moisture.